I have seen this error before and it was the result of either timing out of DocuSign or losing internet connectivity. It may have saved an earlier draft but there is the possibility it cannot be saved and you would need to start over.

So you may need to Discard the changes, check your Drafts folder first and if you do not find an envelope, you may need to create the envelope again, saving often if the Internet connectivity is poor or the timeout is low in DocuSign.

Also may have been sent by another account user while you had the envelope open for edits etc.

We saw this error when trying to submit a Correction today. Following David's comments above, we eventually "discarded" the edits with the intention of starting the corrections over.

But when we went to correct the envelope again, it appeared that the original corrections had, in fact, been made (a signer had been removed and a new signer added, 10 minutes prior when we originally hit the Correct button) -- even though we had received the error, the page where we added the signatures had not closed, and we had later clicked to "discard" the edits.

So, this was not a helpful error message. But, I would second David's advice to discard the changes / close out of the Correct page and check whether it succeeded (and try again, if not).